Apparatus for mixing concrete under pressure



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R. C. STUBBS APPARATUS FOR MIXING CONCRETE UNDER PRESSURE Filed Jan. 23, 1925 INVENTOR Patented Aug. 2d, 1924..

UNlTED STATES ROBERT C. STUBBS,

or marinas, rm.

APPARATUS FOR MIXING CONCRETE UNDER PRESsSURE.

Application filed January 23, 1923. Serial No. $14,838.

To all whom it may concern:

Be it known that 1, ROBERT C. S'I'UBBS, a citizen of the United States, residing at Dallas, in the county of Dallas and State of Texas, have invented certain new and useful Improvements in Apparatus for Mixing Concrete Under Pressure, of which'the following is a specification.

My invention relates to concrete mixers and more particularly to apparatus for mixing concrete under pressure; and the object is to provide means for mixing concrete under pressure SHlllClGIlt to overcome gravity and the advantage is that the quality of the concrete is generally improved and the process of mixing concrete is simplified and made less expensive and the ingredients are more thoroughly mixed and the binder elements are made to cling on all the surfaces of the large aggregate and so leave less space for surplus moisture and air. Another advantage is that provision is made for accurately determining the amount of water necessary and admitted to the other ingredients, and for measuring accurately the volume of'mixed concrete in each batch. Other objects and advantages will be fully explained in the following descri tion and the invention will be more. particu arly pointed out in the claims.

Reference is had to the accompan ing drawings which form a part of this app ication.

Fig. 1 is a longitudinal section of the drum used in the process, showing the interior mechanism. Fig. 2 is a cross-section of the drum, showing an end View of the spiral agitators or vanes. Fig. 3 is a broken sectional view, showing the construction of the spirals or vanes. Fig. 4 is a detail view, illustrating the means for causing vibrations in the helicalvvanes.

Similar characters of reference are used to indicate the same parts throughout the several views.

For the purpose of carrying out the mixing of concrete accordin to this invention, a drum, preferably cylin rical, is employed and this drum 1 is stationarily mounted and is provided with a receiving opening 2 and a discharge opening 3. A small hopper 4 may be used for feeding material to the drum and a discharge chute 5, is provided at the discharge end of the drum 1. A slidable door or gate 6 is slidably connected to the end of the drum for closing the discharge opening 3 during compression and mixing. The door 6 may be held closed by the pressure of the material on the door. The door slides in ways 7 at the upper end of chute 5; The opening 2 is closed during a compression and mixing period. A sliding'cover 8' moves through the side of the hopper 4 and in ways 9 for closing the opening 2.

A helical or spiral formof vanes or agitators is employed. An outer vane 10 and an inner vane 11 are employed. The vanes are preferably rectangular in cross-sectlon, as shown in Fig. 3, and are preferably made of spring metal. The obJe'ct of the two vanes is to move the material in the drum in opposite directions. The outer vane is slightly inclined inwardly and the inner vane 11 is sli htly inclined outwardly, reference being lied to rectangular cross-sectional structure, the vanes being of appreciable width. The outer vane throws the material inwardly and towards the discharge end of the drum in operation and the inner vane 11 throws the material outwardly and back towards the closed or receiving end of the drum. Both vanes are fixedly connected with a driving shaft 12 and are driven by this shaft in the same direction. The outer vane may be left hand and the inner vane right hand and vice versa, but both should not be the same. A gear wheel 13 is rigid with shaft 12 and meshes with a pinion 14 which is driven by a motor 15. The construction and arrangement of the vanes cause the material to be thrown in opposite directions. The pinion 14 should be of suficient width to permit axial movement of the shaft 12 and wheel 13 so that the outer vane 10 may be made to revolve close to the end of the drum. The vanes may be provided with metal plates 21 to aid in the agitation of the material.

In order to prevent any vacancy or air pockets in the drum during operation, a plunger or compressor 16 is employed and more or less force or power may he applifl to the compressor 16 to secure the necessary pressure to force the compressor within the material in the drum to expand the material throughout the interior of the drum. Su'ficient pressure to overcome gravity in the mixture should be em loyed. The power applied may be furnished by a spring prising a drum in a fixed position and provided with closable inlet and discharge open-' ings, an outer helical vane for moving the material in said drum in one direction and an'inner helical vane for moving the mate rial in the opposite direction, means for driving said vanes, and a compressor for applying pressure to said material simultaneously with the moving thereof. 4

6. A machine for mixing concrete and other plastic material comprising a drum in a fixed position, a flat helical vane revolvin in said drum, and independently movab e means for applying pressure to the material in said drum. 7

7. In a drum fixed against movement and provided with closable and discharge openlngs, a fiat helical vane revolving in said drum for movin the material in the central portion of said rum towards one end thereof and a flat helical vane revolving in said drum for moving the material in the outer portion of the material in the opposite direction simultaneously with the movement in the central portion and solid mechanical means for applying pressure throughout the mass during a mixing operation.

8. A machine for mixing concrete and other plastic material comprising a drum fixed against movement, means for moving material in said drum in all parts thereof and a plunger for applyingpressure to the.

entire mass of material durlng the moving thereof and for preventing any vacancy in the drum.

9. A machine for mixing concrete and other plastic material comprising a drum fixed against movement, means for movin material throughout the interior thereo and a movable compressor for applying pressure to the material during the moving thereoffor forcing all air; out of the materialand for preventing any vacancy in said drum during a mixing operation.

10. A machine for mixing concrete. and other plastic material comprising a drum fixed against movement, means for moving material throughout the interior thereof, a

and means for applying pressure through-.

out the mass for preventing any vacancy in said drum and for compacting the binding material on the coarse aggregate.

12. A machine for mixing concrete and other plastic material comprising a drum fixed against movement, a revolving shaft projecting in said drum, a right hand helical vane fixedly, connected with said shaft and a left hand helical vane fixedly connected with said shaft and surrounding said right hand vane for moving material in said drum in opposite directions and mixing the material, and means for exerting pressure on said material simultaneously with the moving thereof.

13. A machine for mixing concrete and other plastic material comprising a drum in fixed position, a flat helical vane having means for revolving it in said drum for mixing material therein, and means connected off-center with said vane revolving means for causing vibrations in said vane.

14. A machine for mixing concrete and other plastic material comprising a drum in a fixed position, an outer left helical vane having means for revolving it in said drum and a right helical vane positioned within said outer vane and revolvlng simultaneously therewith, and means connected off center with said vane revolving means for causing vibrations in said vanes, during operation.

In testimony whereof, I set my hand this 16th day of January, 1923.

ROBERT C. STUBBS- 

